JP4482499B2 - Braking force distribution method and vehicle brake control device - Google Patents

Description

  The present invention relates to a braking force distribution method and a vehicle brake control device.

  When braking force is applied to the front wheel brake and rear wheel brake in an automobile such as an automobile, the center of gravity of the vehicle moves forward and the ground contact load of the rear wheel becomes smaller, so the rear wheel tends to lock. There is a problem that it is easy to become.

  In order to deal with such problems, the brake force of the front wheel brake and the brake force of the rear wheel brake are appropriately distributed according to load changes due to changes in loading conditions and deceleration. A braking force distribution method that stabilizes the dominance of the vehicle has been proposed.

  Such a braking force distribution method has been realized by providing a proportional hydraulic valve (proportional valve) in the brake pipe. However, in recent years, a braking force is applied to a vehicle brake control device capable of anti-lock brake control. This is realized by installing control logic for distribution.

For example, in Patent Document 1, when the value obtained by subtracting the wheel speed of the rear wheel from the wheel speed of the front wheel exceeds a first specified value, the brake fluid pressure of the rear wheel is reduced to reduce the rear wheel against the braking force on the front wheel side. Decreasing the ratio of the braking force on the wheel side and increasing the brake fluid on the rear wheel when the ratio falls below the second specified value smaller than the first specified value, the braking force on the rear wheel side with respect to the braking force on the front wheel side A braking force distribution method for increasing the ratio is disclosed. That is, in the braking force distribution method of Patent Document 1, the target wheel speed targeted by the rear wheel is the actual wheel speed of the front wheel, and the actual wheel speed of the rear wheel follows the wheel speed of the front wheel. The distribution of the braking force on the rear wheel side and the braking force on the front wheel side is adjusted by controlling the braking force on the rear wheel. The wheel speed can be obtained by multiplying the wheel rotation speed (angular speed) detected by the wheel speed sensor attached to the wheel by the wheel radius (hereinafter referred to as “tire radius”).
JP 2003-118552 A

  By the way, not only when tires with different diameters are attached to the front and rear wheels, but also when the degree of wear is different between the front wheels and the rear wheels or when the air pressure is different, the tire radius of the front wheels and the tire radius of the rear wheels If there is a difference, an inevitable difference occurs between the rotational speed of the front wheels and the rotational speed of the rear wheels, regardless of the presence or absence of locking. For this reason, if the actual tire radius of each wheel is not grasped, a difference occurs in the wheel speed obtained by multiplying the rotational speed by the tire radius.

  Even if the tire radii of the front and rear wheels are the same, the turning radii are different between the front wheels and the rear wheels during turning, so the rotation speed of the front wheels (wheel speed) and the rotation speed of the rear wheels (wheels) There is an unavoidable difference in speed.

  In other words, the value obtained by subtracting the wheel speed of the rear wheel from the wheel speed of the front wheel includes an error due to a difference in the tire radius of the front and rear wheels. When the power is increased or decreased, the solenoid valve provided in the brake hydraulic pressure circuit operates more than necessary, and as a result, the operating noise causes discomfort to the passenger, and further, the driver's braking fee is increased. There is a risk of damage to the ring.

  From such a viewpoint, the present invention is a braking force distribution method for distributing the braking force on the front wheel side and the braking force on the rear wheel side, and there is an unavoidable difference between the rotational speed of the front wheel and the rotational speed of the rear wheel. It is an object of the present invention to provide a braking force distribution method capable of appropriately adjusting the distribution of the braking force on the front wheel side and the braking force on the rear wheel side even if it exists. It is an object of the present invention to provide a vehicle brake control device capable of realizing a power distribution method.

The braking force distribution method according to the present invention that solves such a problem is to control the braking force for each rear wheel so that the actual wheel speed of the left and right rear wheels follows each target wheel speed, a brake control method for adjusting the proportion of the braking force and front wheel braking force on the rear wheel side, of the rear wheels to be used this time based on the target wheel speed of the wheel after the actual deceleration amount and the previous use of the front wheel A target wheel speed is calculated.

  In short, the braking force distribution method according to the present invention uses the previous target wheel speed of the rear wheel as a reference without setting the actual wheel speed of the front wheel as the reference when setting the current target wheel speed of the rear wheel. In addition, there is a feature in that the current target wheel speed of the rear wheel is calculated based on the previous target wheel speed and the actual deceleration amount of the front wheel. In this way, even if there is an inevitable difference between the rotational speed of the front wheels (wheel speed) and the rotational speed of the rear wheels (wheel speed), the braking force for the front wheels and the braking force for the rear wheels are distributed. Can be adjusted appropriately. The deceleration amount means an amount of deceleration during the calculation cycle (that is, the time from “previous” to “present”).

The actual deceleration amount of the front wheels may be set as the target deceleration amount of each rear wheel, and the target wheel speed of the rear wheel used this time may be obtained by subtracting the target deceleration amount from the target wheel speed of the rear wheel used last time. . In this way, the target wheel speed of the rear wheel decreases at the same rate as the actual wheel speed of the front wheel.

  In addition, when the actual deceleration amount of at least one of the left and right front wheels is larger than the threshold value, a predetermined deceleration amount may be set as the target deceleration amount. In this case, for example, when the actual deceleration amount of the front wheels is larger than the threshold value, such as when the front wheels tend to be locked, the target wheel speed of the rear wheels using the deceleration amount of the front wheels larger than the threshold value. The problem of setting is eliminated.

In addition, a vehicle brake control device according to the present invention that solves the above-described problems is a vehicle brake control device that can adjust the distribution of the braking force of the wheel brake on the rear wheel side and the braking force of the wheel brake on the front wheel side. A braking force distribution control unit for controlling the braking force for each rear wheel so that the actual wheel speeds of the left and right rear wheels follow the respective target wheel speeds, and each of the above-mentioned values based on the actual deceleration amount of the front wheels. The target rear wheel deceleration amount setting unit for setting the target deceleration amount of the rear wheel and the target deceleration amount set by the target rear wheel deceleration amount setting unit are subtracted from the target wheel speed of the rear wheel used last time and used this time. And a target wheel speed calculation unit that calculates a target wheel speed of the rear wheel.

  According to such a vehicle brake control device, even if there is an unavoidable difference between the rotational speed of the front wheel and the rotational speed of the rear wheel, the braking force for the front wheel and the braking force for the rear wheel are present. It becomes possible to adjust power distribution appropriately.

The target rear wheel deceleration amount setting unit may set the actual deceleration amount of the front wheels as the target deceleration amount of the rear wheels. Further, the target wheel speed calculation unit calculates a target wheel speed of the rear wheel to be used this time by subtracting the target deceleration amount set by the target rear-wheel deceleration amount setting section from the target wheel speed of the wheel after last used You may do.

  The target rear wheel deceleration amount setting unit sets a predetermined deceleration amount as a target deceleration amount for each of the rear wheels when an actual deceleration amount of at least one of the left and right front wheels is larger than a threshold value. It may be. In this case, for example, when the actual deceleration amount of the front wheels is larger than the threshold value, such as when the front wheels tend to be locked, the target wheel speed of the rear wheels using the deceleration amount of the front wheels larger than the threshold value. The problem of setting is eliminated.

  According to the braking force distribution method of the present invention, even if there is an inevitable difference between the rotational speed of the front wheels (wheel speed) and the rotational speed of the rear wheels (wheel speed), the braking force of the front wheels and the rear It is possible to appropriately adjust the distribution of the braking force of the wheels.

  Similarly, according to the vehicle brake control device of the present invention, even if there is an unavoidable difference between the rotational speed of the front wheels and the rotational speed of the rear wheels, the braking force of the front wheels and the braking force of the rear wheels. Can be adjusted appropriately.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, the vehicle brake control device U1 according to the present embodiment includes wheel brakes FR, FL that brake left and right front wheels F, F and wheel brakes RL, RR that brake left and right rear wheels R, R. Independent antilock brake control (hereinafter referred to as “ABS control”) of the wheel brakes FR, RL, RR, FL and wheel brake RR on the rear wheel R side by controlling the magnitude of the brake fluid pressure acting on the rear wheel R , RL, and braking force distribution control (hereinafter referred to as “EBD control”) for adjusting the distribution of braking force of the front wheel F and the braking force of the wheel brakes FR, FL on the front wheel F side. A hydraulic unit 10 provided with various parts and brake fluid flow paths, and a control device 20 for controlling the various parts of the hydraulic unit 10 are provided.

  The hydraulic unit 10 is interposed between a master cylinder M that is a hydraulic source and wheel brakes FR, RL, RR, FL. As shown in FIG. 2, four wheel brakes FR, RL are provided. , RR, FL, a brake system K1 for applying braking force to the two wheel brakes FR, RL and a brake system K2 for applying braking force to the remaining two wheel brakes RR, FL are provided.

  The master cylinder M generates a hydraulic pressure corresponding to the pedaling force applied to the brake pedal P, which is a brake operator, and includes two output ports M1 and M2 corresponding to the two brake systems K1 and K2. ing.

  Since the brake systems K1 and K2 have substantially the same configuration, the brake system K1 will be mainly described below, and the brake system K2 will be described as appropriate.

  The brake system K1 is provided with two control valve means V, V, a reservoir 4, a pump 5, a motor 6, a damper 7, and an orifice 8 corresponding to the wheel brakes FR, RL.

  In the following, the flow path (oil path) from the master cylinder M to the control valve means V, V is referred to as “output hydraulic pressure path A”, and the flow path from the control valve means V, V to the wheel brakes FR, RL. Is referred to as “wheel hydraulic pressure path B”. Further, the flow path from the pump 5 to the output hydraulic pressure path A is referred to as “discharge hydraulic pressure path C”, and the flow path from the control valve means V, V to the pump 5 is referred to as “open path D”.

  The control valve means V is a pressure-increasing state in which the brake fluid is allowed to flow from the output hydraulic pressure path A to the wheel hydraulic pressure path B while blocking the outflow to the open path D, and from the output hydraulic pressure path A to the wheel hydraulic pressure path. A depressurized state that allows inflow to the open path D while blocking the inflow of brake fluid to B, and outflow to the open path D while blocking inflow of brake fluid from the output hydraulic pressure path A to the wheel hydraulic pressure path B It has a function of switching the holding state that shuts off the valve, and is configured to include an inlet valve 1, an outlet valve 2, and a check valve 3.

  The inlet valve 1 is a normally open electromagnetic valve interposed in a flow path from the output hydraulic pressure path A to the wheel hydraulic pressure path B. When the valve 1 is in the open state, the wheel fluid is supplied from the output hydraulic pressure path A side. The brake fluid is allowed to flow into the pressure passage B, and is shut off when the valve is closed. The normally open type electromagnetic valve constituting the inlet valve 1 has an electromagnetic coil for driving the valve body electrically connected to the control device 20, and excites the electromagnetic coil based on a command from the control device 20. Then, the valve is closed, and when it is demagnetized, the valve is opened.

  The outlet valve 2 is a normally closed electromagnetic valve interposed in a flow path from the wheel hydraulic pressure path B to the open path D, and when in the closed state, the wheel hydraulic pressure path B side to the open path D side. Shut off the flow of brake fluid to the valve and allow it when the valve is open. The normally closed electromagnetic valve constituting the outlet valve 2 has an electromagnetic coil for driving the valve body electrically connected to the control device 20, and excites the electromagnetic coil based on a command from the control device 20. Then, it opens, and when it is demagnetized, it closes.

  The check valve 3 is a one-way valve that allows only inflow of brake fluid from the wheel hydraulic pressure passage B side to the output hydraulic pressure passage A side, and is connected in parallel with each inlet valve 1.

  The reservoir 4 is provided in the release path D, and has a function of temporarily storing brake fluid that is released when each outlet valve 2 is opened.

  The pump 5 is interposed between the discharge hydraulic pressure path C leading to the output hydraulic pressure path A and the release path D, is driven by the rotational force of the motor 6, and brake fluid temporarily stored in the reservoir 4. Is discharged into the discharge hydraulic pressure path C. As a result, the brake fluid stored in the reservoir 4 is recirculated to the output hydraulic pressure path A and the like.

  The motor 6 is a common power source for the pump 5 in the brake system K1 and the pump 5 in the brake system K2, and operates based on a command from the control device 20.

  The damper 7 and the orifice 8 attenuate the pulsation of the brake fluid discharged from the pump 5 by the cooperative action.

Based on the outputs from the front wheel speed sensor SF attached to each front wheel F (see FIG. 1) and the rear wheel speed sensor SR attached to each rear wheel R (see FIG. 1), the control device 20 controls the inlet valve 1. The control of the opening and closing of the outlet valve 2 and the operation of the motor 6 are omitted. Although not shown, the CPU includes a central processing unit (CPU), a RAM, a ROM and an input / output circuit, and a front wheel speed sensor SF. As shown in FIG. 3, a front wheel speed calculation unit is performed by performing various arithmetic processes based on the input from the rear wheel speed sensor SR and the control program stored in the ROM, various threshold values (reference values), and the like. 21, rear wheel speed calculation unit 22, front wheel deceleration amount calculation unit 23, rear wheel deceleration amount calculation unit 24, target rear wheel deceleration amount setting unit 25, target wheel speed calculation unit 26, target wheel speed storage unit 27, determination unit 28 , Braking force distribution control Functions as 29 and anti-lock control unit 30. The front wheel speed sensors SF and SF output electrical signals corresponding to the rotational speeds ω _FR and ω _FL to the front wheel speed calculation unit 21, respectively. Similarly, the rear wheel speed sensors SR, SR output electrical signals corresponding to the rotational speeds ω _RR , ω _RL to the rear wheel speed calculation unit 22, respectively.

The front wheel speed calculation unit 21 calculates the right front wheel on the basis of the electrical signal output from the front wheel speed sensor SF of the right front wheel F at every calculation cycle Δt (time from the “previous” calculation to the “current” calculation). It calculates the wheel speed V _FR of F, calculates the wheel speeds V _FL of the front wheel F of the left based on the electric signal output from the front wheel speed sensor SF of the left front wheel F, the resulting wheel speed V _FR, V _FL is output to the front wheel deceleration amount calculation unit 23, the determination unit 28, and the antilock control unit 30. The wheel speed V _FR of the right front wheel F is calculated by multiplying the electrical signal output from the right front wheel speed sensor SF by a predetermined calibration coefficient to calculate the rotation speed ω _FR of the right front wheel F. It is calculated by multiplying ω _FR by a tire radius r stored in advance in a ROM (not shown). The same applies to the wheel speed V _FL of the left front wheel F.

The rear wheel speed calculation unit 22 calculates the wheel speed V _RR of the right rear wheel R based on the electrical signal output from the right rear wheel speed sensor SR for each calculation cycle Δt, and also the left rear wheel speed. The wheel speed _VRL of the left rear wheel R is calculated based on the electrical signal output from the sensor SR, and the obtained wheel speeds _VRR and _VRL are used as the rear wheel deceleration amount calculation unit 24 and the target wheel speed calculation unit 26. To the determination unit 28 and the antilock control unit 30. The wheel speed V _RR of the right rear wheel R is calculated by calculating the rotational speed ω _RR of the rear wheel R by multiplying the electrical signal output from the right rear wheel speed sensor SR by a predetermined calibration coefficient. It is calculated by multiplying the tire radius r which is previously stored in a ROM (not shown) to the velocity omega _RR. The same applies to the wheel speed _VRL of the left rear wheel R.

The front wheel deceleration amount calculation unit 23 calculates the actual deceleration amounts G _FR and G _FL for each of the left and right front wheels F and F every calculation cycle Δt, and uses the obtained deceleration amounts G _FR and G _FL as target rear wheels. Output to the deceleration amount setting unit 25. The wheel speed of the right front wheel F at the time t (n−1) (previous wheel speed) is V _FR (n−1), and the wheel speed of the right front wheel F at the time t (n) after the calculation cycle Δt ( If the current wheel speed) is V _FR (n), the right front wheel deceleration amount G _FR (n) can be calculated by the following equation (see FIG. 4).
G _FR (n) = V _FR (n) −V _FR (n−1)
Similarly, the deceleration amount G _FL (n) of the left front wheel F can be calculated by the following equation.
G _FL (n) = V _FL (n) −V _FL (n−1)

  In the following description, “n−1” means “previous” and “n” means “current”.

The rear wheel deceleration amount calculation unit 24 calculates the actual deceleration amounts G _RR and G _RL for each of the left and right rear wheels R and R every calculation cycle Δt, and determines the obtained deceleration amounts G _RR and G _RL . To the unit 28. The wheel speed of the right rear wheel R at the time t (n−1) (previous wheel speed) is V _RR (n−1), and the wheel of the right rear wheel R at the time t (n) after the calculation period Δt. Assuming that the speed (current wheel speed) is V _RR (n), the right rear wheel deceleration amount G _RR (n) can be calculated by the following equation.
G _RR (n) = V _RR (n) −V _RR (n−1)
Similarly, the deceleration amount G _RL (n) of the left rear wheel R can be calculated by the following equation.
G _RL (n) = V _RL (n) −V _RL (n−1)

The target rear wheel deceleration amount setting unit 25 determines the rear of each of the left and right rear wheels R and R based on the actual deceleration amounts G _FR and G _FL of the front wheels F and F output from the front wheel deceleration amount calculation unit 23. The current target deceleration amounts TG _RR and TG _RL of the wheel R are set, and the obtained target deceleration amounts TG _RR and TG _RL are output to the target wheel speed calculation unit 26. The target deceleration amount TG _RR (n) of the right rear wheel R from the time t (n−1) to the time t (n) is, for example, the actual value of the front wheel F on the same side (that is, the right side) at the same time. Can be calculated by the following equation based on the deceleration amount G _FR (n).
TG _RR (n) = k ₁ · G _FR (n)
Here, k ₁ is a constant. For example, if k ₁ = 1, the target deceleration amount TG _RR (n) of the right rear wheel R is equal to the actual deceleration amount G _FR (n) of the right front wheel F. Will be equal.
Similarly, the target deceleration amount TG _RL (n) of the left rear wheel R can be calculated by the following equation.
TG _RL (n) = k ₂ · G _FL (n)
Here, k ₂ is a constant. For example, if k ₂ = 1, the target deceleration amount G _RL (n) of the left rear wheel R is equal to the actual deceleration amount G _FL (n) of the left front wheel F. Will be equal.

The target deceleration amounts TG _RR (n), TG _RL (n) of the rear wheels R are based on the average values of the actual deceleration amounts G _FR (n), G _FL (n) of the left and right front wheels F, F. You may calculate by following Formula.
TG _RR (n) = TG _RL (n) = k ₃ · {G _FR (n) + G _FL (n)} / 2
Here, k ₃ is a constant, and if k ₃ = 1, the target deceleration amount TG _RR (n), TG _RL (n) of the rear wheel R is the actual deceleration amount G _FR of the left and right front wheels F, F. (N), G _FL (n) is equal to the average value.

Further, the target deceleration amounts TG _RR (n), TG _RL (n) of the rear wheels R are based on the smaller of the actual deceleration amounts G _FR (n), G _FL (n) of the left and right front wheels F, F. You may calculate by following Formula.
TG _RR (n) = TG _RL (n) = k ₄ · min {G _FR (n), G _FL (n)}
Here, k ₄ is a constant, and if k ₄ = 1, the target deceleration amount TG _RR (n), TG _RL (n) of the rear wheel R is the actual deceleration amount G _FR of the left and right front wheels F, F. (N), G _FL (n) is equal to the smaller one.

The target rear wheel deceleration amount setting unit 25 determines that the actual deceleration amount G _FR (n), G _FL (n) of at least one of the left and right front wheels F, F is larger than a preset threshold value α. The predetermined deceleration amount G ′ is set to the target deceleration amounts TG _RR (n) and TG _RL (n).

The target wheel speed calculation unit 26 sets the target deceleration amount TG _RR (n), TG _RL (n) set by the target rear wheel deceleration amount setting unit 25 and the previously used target for each of the left and right rear wheels R, R. Based on the wheel speeds TV _RR (n−1) and TV _RL (n−1), the target wheel speeds TV _RR (n) and TV _RL (n) used this time are calculated, and the obtained target wheel speed TV _{RR is} obtained. (N), TV _RL (n) is output to the target wheel speed storage unit 27. In the present embodiment, the target wheel speed calculation unit 26 calculates the target deceleration amounts TG _RR (n), TG _RL (n) from the previously used target wheel speeds TV _RR (n−1), TV _RL (n−1). To calculate target wheel speeds TV _RR (n), TV _RL (n) to be used this time. More specifically, the target wheel speed calculation unit 26 uses the previously used target wheel speeds TV _RR (n−1) and TV _RL (n−1) stored in the target wheel speed storage unit 27 described later. Based on the read target wheel speeds TV _RR (n−1) and TV _RL (n−1), the target wheel speeds TV _RR (n) and TV _RL (n) used this time are calculated according to the following equation. (See FIG. 4).
TV _RR (n) = TV _RR (n-1) -TG _RR (n)
_{TV RL (n) = TV RL} (n-1) -TG RL (n)

Further, as shown in FIG. 4, the target wheel speed calculation unit 26 determines the current speed of the rear wheel R from the actual wheel speed V _RR (n) of the right rear wheel R detected this time (time t (n)). The target wheel speed TV _RR (n) is subtracted to calculate the speed difference ΔV _RR (n) and output to the determination unit 28. Similarly, the speed difference ΔV _RL (n) is calculated for the left rear wheel R and is output to the determination unit 28.

The target wheel speed storage unit 27 stores the target wheel speeds TV _RR (n) and TV _RL (n) output from the target wheel speed calculation unit 26 as target wheel speeds to be used next time.

The target wheel speed storage unit 27 determines the actual wheel speeds V _RR and V _{RL of} the rear wheels R and R calculated by the rear wheel speed calculation unit 22 until the determination unit 28 determines to execute the EBD control. Is the initial value of the target wheel speed of the rear wheels R, R (that is, the previous target wheel speed TV _RR (0), TV _RL when calculating the initial target wheel speed TV _RR (1), TV _RL (1)). (0)). Note that the target wheel speeds TV _RR (0) and TV _RL (0) are rewritten every calculation period Δt until the EBD control is started.

The determination unit 28 determines whether to execute EBD control of the braking force of the front and rear wheel brakes. In the present embodiment, the determination unit 28 includes the target wheel speed TV _RR (TV _RL ) calculated by the target wheel speed calculation unit 26 and the actual wheel speed V _{RR of} the rear wheel R calculated by the rear wheel speed calculation unit 22. When the difference from (V _RL ) is a predetermined value or more and the actual deceleration amount G _RR (G _RL ) of the rear wheel R calculated by the rear wheel deceleration amount calculation unit 24 is a predetermined value or more, It is determined that the condition for starting the EBD control is satisfied, and the speed differences ΔV _RR (n) and ΔV _RL (n) calculated by the target wheel speed calculation unit 26 are output to the braking force distribution control unit 29.

The braking force distribution control unit 29 sets the rear wheels so that the actual wheel speeds V _RR and V _RL of the left and right rear wheels R and R follow the target wheel speeds TV _RR (n) and TV _RL (n). The braking force for R and R is controlled.

The right rear wheel R will be described as an example. The braking force distribution control unit 29 controls the control valve means V (corresponding to the right rear wheel R (wheel brake RR)) according to the magnitude of the speed difference ΔV _RR (n). (See FIG. 2). Specifically, when the speed difference ΔV _RR (n) is greater than or equal to a preset pressure increase reference value β ₁ (β ₁ ≦ ΔV _RR (n)), the inlet valve 1 of the control valve means V is opened. When the control is performed to close the outlet valve 2 and the speed difference ΔV _RR (n) is larger than the preset pressure reduction reference value β ₂ and less than the pressure increase reference value β ₁ (β ₂ <ΔV _RR (n) <β ₁ ), the brake hydraulic pressure acting on the wheel brake RR by executing the control for closing the inlet valve 1 of the control valve means V and closing the outlet valve 2. When the speed difference ΔV _RR (n) is equal to or less than the pressure reduction reference value β ₂ (ΔV _RR (n) ≦ β ₂ ), the inlet valve 1 of the control valve means V is closed and the outlet valve The brake fluid pressure acting on the wheel brake RR is reduced by executing the control to open the valve 2. The

  When the inlet valve 1 is opened and the outlet valve 2 is closed, the flow path from the master cylinder M to the wheel brake RR is in communication, so that the brake generated due to the operating force of the brake pedal P is generated. The hydraulic pressure acts on the wheel brake RR as it is, and as a result, the brake hydraulic pressure acting on the wheel brake RR is increased. When the inlet valve 1 and the outlet valve 2 are closed, the brake fluid is confined in the flow path closed by the inlet valve 1 and the outlet valve 2, so that the brake fluid pressure acting on the wheel brake RR is constant. Retained. Further, when the inlet valve 1 is closed and the outlet valve 2 is opened, the brake fluid that has been acting on the wheel brake RR flows into the reservoir 4 through the release path D, so that it acts on the wheel brake RR. The brake fluid pressure is reduced.

  The braking force distribution control unit 29 ends the EBD control when the ABS control is executed in the antilock control unit 30 described later.

  The anti-lock control unit 30 corresponds to the control valve means V corresponding to the wheel brakes FR and FL of the front wheels F and F which are likely to be locked or the wheel brakes RR and RL of the rear wheels R and R which are likely to be locked. The control valve means V to control is controlled. More specifically, the anti-lock control unit 30 determines whether each wheel is likely to be locked based on the vehicle body speed and the wheel speed of each wheel, and is likely to be locked. It controls the opening and closing of the inlet valve 1 and the outlet valve 2 of the control valve means V corresponding to the wheel brake of the wheel determined to be present. By executing such control, the brake fluid acting on the wheel brake is controlled. The pressure is reduced, increased or maintained.

  When the anti-lock control unit 30 determines that at least one of the front wheels F, F and the rear wheels R, R is likely to be locked, a flag indicating that the ABS control is being executed is displayed. Set to “1”.

The vehicle brake control device U1 configured as described above is set so that a control program corresponding to the flowchart shown in FIG. 5 is executed when an unillustrated ignition switch is turned on. When the condition is satisfied, the braking force for the rear wheels R and R is controlled so that the actual wheel speeds V _RR and V _RL of the left and right rear wheels R and R follow the respective target wheel speeds TV _RR and TV _RL. Thus, the distribution of the braking force on the rear wheels R and R and the braking force on the front wheels F and F is adjusted.

The operation of the vehicle brake control device U1 will be described in more detail with reference to the block diagram shown in FIG. 3 and the flowchart shown in FIG. When the control program is executed, first, as shown in step 101, the front wheel speed calculation unit 21 calculates the wheel speeds V _FR and V _FL for each of the two front wheels F and F, and the rear wheel speed calculation unit 22 calculates them. Wheel speeds V _RR and V _RL are calculated for each of the two rear wheels R and R.

Next, the process proceeds to step 102, where the actual deceleration amounts G _FR and G _FL are calculated for each of the two front wheels F and F by the front wheel deceleration amount calculation unit 23, and the two rear wheels R are calculated by the rear wheel deceleration amount calculation unit 24. , R, the actual deceleration amounts G _RR , G _RL are calculated.

Subsequently, the process proceeds to step 103, where it is determined whether or not ABS control is being executed. If it is determined that ABS non-control is being performed (Yes), the process proceeds to step 104. That is, if the flag set by the antilock control unit 30 is “0”, it is determined that the ABS is not controlled (Yes), and if the flag is “1”, the ABS is not being controlled (No). (That is, it is determined that ABS control is being performed). If it is determined in step 103 that the ABS is not under control (No), the target wheel speed TV _RR (n−1) stored in the target wheel speed storage unit 27 is used to prioritize the ABS control. ), TV _RL (n−1) is reset, and the process returns to Step 101.

  Step 104 and subsequent steps are exemplified when the right rear wheel R is controlled, and the left rear wheel R is the same as that of the right rear wheel R, and thus detailed description thereof is omitted.

In step 104, the target rear wheel deceleration amount setting unit 25 sets the current target deceleration amount of the right rear wheel R based on the actual deceleration amount G _FR (n) of the front wheel F output from the front wheel deceleration amount calculation unit 23. TG _RR (n) is set.

Although illustration is omitted, in step 104, the target rear wheel deceleration amount setting unit 25 determines whether or not the actual deceleration amount G _FR (n) of the front wheel F is larger than a preset threshold value α. When it is determined that the deceleration amount G _FR (n) is larger than the threshold value α, a predetermined deceleration amount G ′ is set as the target deceleration amount TG _RR (n).

Next, the process proceeds to step 105, where the target wheel speed calculation unit 26 reads the previously used target wheel speed TV _RR (n−1) stored in the target wheel speed storage unit 27.

Subsequently, the process proceeds to step 106 where the target wheel speed calculation unit 26 calculates the target wheel speed TV _RR (n) to be used this time. The target wheel speed TV _RR (n) used this time is, for example, the target deceleration amount TG _RR (n) set by the target rear wheel deceleration amount setting unit 25 from the previously used target wheel speed TV _RR (n−1). Obtained by subtraction. The target wheel speed TV _RR (n) used this time is temporarily stored in the target wheel speed storage unit 27.

The target wheel speed TV _RR (1) used at the first EBD control (time T ₁ in FIG. 6) is the actual rear wheel R calculated by the rear wheel speed calculation unit 22 at time (T ₁ -Δt). The value obtained by subtracting the target deceleration amount TG _RR (1) set by the target rear wheel deceleration amount setting unit 25 from the vehicle wheel speed V _RR (0). That is, the first target wheel speed TV _RR (1) is calculated by subtracting the target deceleration amount TG _RR (1) from the actual wheel speed V _RR (0) of the rear wheel R itself to be controlled. Calculates the current target wheel speed T _RR (n) by subtracting the current target deceleration amount TG _RR (n) from the previous target wheel speed T _RR (n−1).

In step 107, the target wheel speed calculation unit 26 subtracts the actual wheel speed V _RR (n) of the right rear wheel R detected at the same time from the current target wheel speed TV _RR (n) of the rear wheel R. Thus, the speed difference ΔV _RR (n) is calculated.

Subsequently, the process proceeds to step 108, where it is determined whether or not the EBD control start condition is satisfied by the determination unit 28, and when it is determined that the EBD control start condition is satisfied (Yes), the process proceeds to step 109. . If it is determined in step 108 that the EBD control execution condition is not satisfied (No), the target wheel speed TV _RR (n−1), TV _RL ( After resetting n-1), the process returns to Step 101.

Subsequently, the process proceeds to step 109, where the braking force distribution control unit 29 determines whether or not the speed difference ΔV _RR (n) is equal to or greater than the pressure increase reference value β ₁ (β ₁ ≦ ΔV _RR (n)). When it is determined that the speed difference ΔV _RR (n) is equal to or greater than the pressure increase reference value β ₁ (Yes), the process proceeds to step 110 where the inlet valve 1 of the control valve means V is opened and the outlet valve 2 Control for closing the valve is executed. When the inlet valve 1 is opened and the outlet valve 2 is closed, the brake fluid pressure generated in the master cylinder M acts on the wheel brake RR (see FIG. 2), so that the brake fluid acting on the wheel brake RR. The pressure is increased.

If it is determined in step 109 that the speed difference ΔV _RR (n) is not equal to or greater than the pressure increase reference value β ₁ (No), the process proceeds to step 111, where the speed difference ΔV _RR (n) is equal to or less than the pressure decrease reference value β _2. Whether or not (ΔV _RR (n) ≦ β ₂ ) is determined, and if it is determined that the speed difference ΔV _RR (n) is equal to or less than the pressure reduction reference value β ₂ (Yes), the process proceeds to Step 112. Then, the control for closing the inlet valve 1 of the control valve means V and opening the outlet valve 2 is executed. When the inlet valve 1 is closed and the outlet valve 2 is opened, the brake fluid flows into the reservoir 4 (see FIG. 2), so that the brake fluid pressure acting on the wheel brake RR is reduced.

If it is determined in step 111 that the speed difference ΔV _RR (n) is not less than or equal to the pressure reduction reference value β ₂ (No) (that is, the speed difference ΔV _RR (n) is greater than the pressure reduction reference value β ₂ and the pressure increase reference When the value is less than β ₁ (β ₂ <ΔV _RR (n) <β ₁ ), the routine proceeds to step 113 where the inlet valve 1 of the control valve means V is closed and the outlet valve 2 is closed. Control is executed. Note that when the inlet valve 1 and the outlet valve 2 are closed, the brake fluid pressure acting on the wheel brake RR is maintained.

  After steps 110, 112, and 113 are executed, the process returns to step 101, and the above steps are repeated.

  With reference to FIG. 6, the braking force distribution method by the vehicle brake control device U1 according to the present embodiment will be described. Here, (a) in FIG. 6 is a graph showing temporal changes in the wheel speeds of the front wheels and rear wheels, and (b) in FIG. 6 is a temporal change in the difference between the actual wheel speed of the rear wheels and the target wheel speed. (C) of FIG. 6 is a graph which shows the time change of the brake hydraulic pressure which acts on a wheel brake.

FIG. 6 illustrates a case where the right rear wheel R is controlled based on the deceleration amount of the right front wheel F. Further, FIG. 6 shows that there is a difference between the tire radius of the front wheel F and the tire radius of the rear wheel R, or because the vehicle is turning, the wheel speed V _FR (rotational speed) of the front wheel F and the rear wheel. The case where an inevitable difference has occurred in the wheel speed V _RR (rotational speed) of R is illustrated, but there is no difference between the wheel speed V _FR of the front wheel F and the wheel speed V _RR of the rear wheel R. However, it goes without saying that the vehicle brake control device U1 and the braking force distribution method according to the present embodiment can be applied.

When braking is started at time T ₀ (the brake pedal P (see FIG. 2) is operated), the difference between the target wheel speed TV _RR and the actual wheel speed V _RR of the rear wheel R is equal to or greater than a predetermined value, The brake fluid pressure of the wheel brake RR of the rear wheel R is increased according to the depression force of the brake pedal P until the EBD control start condition that the actual deceleration amount _GRR is equal to or greater than a predetermined value is satisfied. When the EBD control and the ABS control are not executed, the inlet valve 1 of the control valve means V is opened and the outlet valve 2 is closed, so that the brake hydraulic pressure generated in the master cylinder M is It acts on the wheel brake RR as it is (see FIG. 2).

In the present embodiment, the starting condition of EBD control are satisfied at time _{T 1,} increasing speed difference between the actual wheel speed _V RR (n) between the current target wheel speed _{TV RR (n) ΔV RR (} n) is until below the pressure reference value beta _1, the inlet valve 1 is opened, the outlet valve 2 is closed (see step 109 and 110 in FIG. 5), the brake fluid pressure of the wheel brake RR continues brake pedal The pressure is increased according to the pedaling force of P.

The inlet valve 1 and the outlet valve 2 are closed from time T _{2 when the} speed difference ΔV _RR (n) falls below the pressure increase reference value β ₁ to time T ₃ below the pressure reduction reference value β ₂ (FIG. 5). Steps 111 and 113), the brake hydraulic pressure of the wheel brake RR is maintained.

From time T ₃ to the speed difference ΔV _{RR (n)} falls below a reduced pressure reference value beta _2, until time T ₄ above the vacuum reference value beta _2, the inlet valve 1 is closed, the outlet valve 2 is opened Therefore (see steps 111 and 112 in FIG. 5), the brake fluid pressure of the wheel brake RR is reduced.

From the time T ₄ the speed difference [Delta] V _{RR which (n)} is greater than the reduced pressure reference value beta _2, until time T ₅ to be pressure increase reference value beta ₁ or more, since the inlet valve 1 and the outlet valve 2 is closed (FIG. 5 (see steps 111 and 113), the brake fluid pressure of the wheel brake RR is maintained.

The time _{T 5} after the speed difference [Delta] V _RR (n) is ₁ or more pressure increase reference value beta, the inlet valve 1 is opened, the outlet valve 2 is closed (see step 109 and 110 in FIG. 5) The brake fluid pressure of the wheel brake RR is increased.

When the inlet valve 1 and the outlet valve 2 of the control valve means V are opened and closed according to such a flow, the brake fluid pressure acting on the wheel brake FR of the front wheel F and the brake fluid pressure acting on the wheel brake RR of the rear wheel R are appropriate. (See (c) of FIG. 6), the actual wheel speed V _RR (n) of the rear wheel R follows the target wheel speed TV _RR (n) (see (a) of FIG. 6). .

When the actual deceleration amount G _RR (n) of the rear wheel R becomes smaller than a predetermined value and the EBD control start condition is not satisfied (see step 108 in FIG. 5), the EBD control is temporarily ended (time T ₆ ). In a state where the EBD control is not executed, the inlet valve 1 is opened and the outlet valve 2 is closed, so that the brake fluid pressure of the wheel brake RR is increased according to the depression force of the brake pedal P. The

Note that the difference between the actual wheel speed V _FR of the front wheel F and the actual wheel speed V _RR of the rear wheel R is equal to or greater than a predetermined value, and the actual deceleration amount G _RR of the rear wheel is equal to or greater than a predetermined value. Is satisfied (time T ₇ ), the EBD control is resumed (steps 109 to 113 in FIG. 5 are executed).

As described above, the brake control method according to the present embodiment performs the actual deceleration amounts V _FR (n), V _FL (n) of the front wheels F, F and the previously used target wheel speed TV _RR (n−1). , TV _RL (n−1) and target wheel speeds TV _RR (n), TV _RL (n) used this time are calculated. That is, in the brake control method according to the present embodiment, the target wheel speeds TV _RR (n) and TV _RL (n), which serve as a reference when increasing or decreasing the braking force of the rear wheel R, are used as the actual wheel speed V of the front wheel F. It is not set based on _FR (n), V _FL (n), but based on the target wheel speeds TV _RR (n−1), TV _RL (n−1) that the rear wheel R has set as the previous target. Therefore, there is an inevitable difference between the rotational speeds ω _FR (n), ω _FL (n) of the front wheels F, F and the rotational speeds ω _RR (n), ω _RL (n) of the rear wheels R, R. Even in this case, it is possible to appropriately adjust the distribution of the braking force for the front wheel F and the braking force for the rear wheel R.

Further, the target rear wheel deceleration amount setting unit 25 determines a predetermined deceleration when the actual deceleration amount G _FR (n), G _FL (n) of at least one of the front wheels F, F is larger than the threshold value α. Since the amount G ′ is set to the target deceleration amount TG _RR (n), TG _RL (n), for example, when the front wheels F, F tend to be locked, the actual deceleration amount G _FR ( n), when G _FL (n) is larger than the threshold value α, the rear wheels R, R using the deceleration amounts G _FR (n), G _FL (n) of the front wheels F, F larger than the threshold value α The problem of setting the target wheel speeds TV _RR (n), TV _RL (n) is eliminated.

  In the present embodiment, the vehicle brake control device U1 of the type that applies the braking force to the wheel brakes using the brake hydraulic pressure is exemplified, but the present invention is not limited to this, and the electric force is used. Of course, a vehicle brake control device that applies braking force to the wheel brakes may be used.

It is a mimetic diagram showing a vehicle carrying a vehicular brake control device concerning this embodiment. 1 is a hydraulic circuit diagram of a vehicle brake control device according to the present embodiment. It is a block block diagram of the control apparatus of the brake control apparatus for vehicles which concerns on this embodiment. It is a graph for demonstrating the calculation method of target wheel speed. It is a flowchart for demonstrating operation | movement of the brake control apparatus for vehicles which concerns on this embodiment. (A) is a graph showing the time change of the wheel speed of the front wheel and the rear wheel, (b) is a graph showing the time change of the difference between the actual wheel speed of the rear wheel and the target wheel speed, and (c) is a wheel brake. It is a graph which shows the time change of the brake fluid pressure which acts.

Explanation of symbols

U1 Vehicle brake control device 1 Inlet valve 2 Outlet valve 10 Hydraulic unit 20 Control device 24 Rear wheel deceleration amount calculation unit 25 Target rear wheel deceleration amount setting unit 26 Target wheel speed calculation unit 29 Braking force distribution control unit

Claims (6)

The distribution of the braking force on the rear wheel side and the braking force on the front wheel side is adjusted by controlling the braking force on each rear wheel so that the actual wheel speeds of the left and right rear wheels follow the respective target wheel speeds. A braking force distribution method,
A braking force distribution method, comprising: calculating a target wheel speed of a rear wheel used this time based on an actual deceleration amount of a front wheel and a target wheel speed of a rear wheel used last time. By controlling the braking force for each of the rear wheels so that the actual wheel speeds of the left and right rear wheels follow the respective target wheel speeds, the braking force of the wheel brakes on the rear wheel side and the wheel brakes on the front wheel side are controlled. A braking force distribution method for adjusting power distribution,
The actual deceleration amount of the front wheel is set as the target deceleration amount of the rear wheel, and the target wheel speed of the rear wheel used this time is obtained by subtracting the target deceleration amount from the target wheel speed of the rear wheel used last time. Braking force distribution method to do.   The braking force distribution method according to claim 2, wherein when a real deceleration amount of at least one of the left and right front wheels is larger than a threshold value, a predetermined deceleration amount is set as the target deceleration amount. A vehicle brake control device capable of adjusting a distribution of a braking force of a wheel brake on a rear wheel side and a braking force of a wheel brake on a front wheel side,
A braking force distribution control unit that controls the braking force for each of the rear wheels so that the actual wheel speeds of the left and right rear wheels follow the respective target wheel speeds;
A target rear wheel deceleration amount setting unit that sets a target deceleration amount of each rear wheel based on an actual deceleration amount of the front wheels;
A target wheel speed calculation unit that calculates a target wheel speed of the rear wheel used this time based on the target deceleration amount set by the target rear wheel deceleration amount setting unit and the target wheel speed of the rear wheel used last time. A vehicle brake control device. The target rear wheel deceleration amount setting unit sets the actual deceleration amount of the front wheels as the target deceleration amount of each rear wheel,
The target wheel speed calculation unit calculates the target wheel speed of the rear wheel used this time by subtracting the target deceleration amount set by the target rear wheel deceleration amount setting unit from the target wheel speed of the rear wheel used last time. The vehicle brake control device according to claim 4.   The target rear wheel deceleration amount setting unit sets a predetermined deceleration amount as a target deceleration amount for each rear wheel when an actual deceleration amount of at least one of the left and right front wheels is larger than a threshold value. The vehicle brake control device according to claim 4 or 5.

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